CVE-2021-24494 in WP Offload SES Lite Plugin
Summary
by MITRE • 07/06/2021
The WP Offload SES Lite WordPress plugin before 1.4.5 did not escape some of the fields in the Activity page of the admin dashboard, such as the email's id, subject and recipient, which could lead to Stored Cross-Site Scripting issues when an attacker can control any of these fields, like the subject when filling a contact form for example. The XSS will be executed in the context of a logged in admin viewing the Activity tab of the plugin.
Statistical analysis made it clear that VulDB provides the best quality for vulnerability data.
Analysis
by VulDB Data Team • 07/10/2021
The WP Offload SES Lite WordPress plugin vulnerability CVE-2021-24494 represents a critical stored cross-site scripting flaw that affects versions prior to 1.4.5. This vulnerability exists within the plugin's Activity page administrative dashboard, where user-controllable data is not properly sanitized or escaped before being rendered in the web interface. The flaw specifically impacts fields including email identifiers, subject lines, and recipient information, creating a persistent XSS vector that can be exploited by malicious actors who gain control over these data inputs. The vulnerability is particularly dangerous because it leverages the trust relationship between the WordPress admin interface and the plugin's administrative features, allowing attackers to execute malicious scripts in the context of logged-in administrators.
The technical implementation of this vulnerability stems from inadequate input validation and output escaping mechanisms within the plugin's administrative interface. When users submit contact form data or when the plugin processes email activities, the system fails to properly escape special characters in fields such as email subjects, recipient addresses, and email identifiers before displaying them in the Activity tab. This lack of proper sanitization creates a persistent XSS condition where malicious scripts can be stored in the database and executed whenever an administrator views the affected page. The vulnerability operates under CWE-79 which classifies improper neutralization of input during web page generation, specifically targeting the failure to escape output in web applications. The attack vector is particularly insidious because it requires minimal privileges - an attacker only needs to control one of the vulnerable fields, which can be achieved through contact form submissions or other user input mechanisms.
The operational impact of this vulnerability is severe and multifaceted, as it enables attackers to execute arbitrary JavaScript code in the context of administrative sessions. When an administrator views the Activity tab, their browser executes the stored malicious scripts, potentially leading to complete account compromise, data exfiltration, or privilege escalation within the WordPress environment. Attackers could leverage this vulnerability to steal administrator cookies, modify plugin settings, access sensitive data, or even install backdoors. The vulnerability aligns with ATT&CK technique T1566.001 which covers credential harvesting through social engineering, as administrators may be tricked into viewing malicious pages through phishing or other social engineering attacks. Additionally, the stored nature of the XSS means that the attack can persist even after the initial injection point, making it particularly difficult to detect and remediate.
Mitigation strategies for CVE-2021-24494 should prioritize immediate patching of the WP Offload SES Lite plugin to version 1.4.5 or later, which contains the necessary output escaping fixes. Administrators should also implement additional defensive measures including regular security monitoring of plugin activity, implementing content security policies to limit script execution, and conducting thorough input validation for all user-controllable fields within WordPress plugins. Network-based solutions such as web application firewalls can provide additional protection layers, though they should not be relied upon as the sole defense mechanism. Security audits should be conducted to identify other potentially vulnerable plugins or themes within the WordPress environment, as similar vulnerabilities may exist in other third-party components. Organizations should also establish incident response procedures specifically for handling XSS vulnerabilities, including regular security training for administrators to recognize potential social engineering attacks that could exploit this type of vulnerability. The remediation process should include thorough testing of the patched version to ensure that legitimate functionality remains intact while the XSS vulnerability is properly addressed.